Timing device for starting a three-phase motor



March 31, 1964 R. H. LEHDE 3,127,433

TIMING DEVICE FOR STARTING A THREE-PHASE MOTOR Filed May 21 1962 2 Sheets-Sheet 1 I I I4 "Ll L2 L3 :51 '9/5 TIMING 32 4 MOTOR Tl T2 T3 INVENTOR.

RIC HARD H. LEHDE ATTORNEY.

March 31, 1964 R. H. LEHDE 3,127,483

TIMING DEVICE F'OR' STARTING A THREE-PHASE MOTOR Filed May 21, 1962 2- Sheets-Sheet 2 INVENTOR. RICHARD H. LEHDE ATTORNEY.

United States Patent 3,127,483 TIMING DEVICE FOR STARTING A THREE-PHASE MOTOR Richard H. Lehde, West Hartford, Conn., assignor to Dayton Co. Inc., West Hartford, Conn. Filed May 21, 1962, Ser. No. 196,245 1 Claim. (Cl. 20038) The present invention relates generally to new and useful improvements and structural refinements in timers and is directed more particularly to the provision of a novel timer means adapted to start a three-phase motor, having general utility in the arts, and to improvements in said timer means wherefore the conventional magnetic starter, generally used in conjunction with a timer, is eliminated.

It will be helpful to an understanding of my invention first to briefly consider some of the essential points and more important features and aspects thereof, so that the same may be kept in mind during subsequent reading of the detailed description of the practical embodiment of my improvements and illustration thereof in the hereunto annexed drawings.

In order to properly and efficiently start a three-phase motor, it is necessary to complete the three circuits to the motor windings as near simultaneously as practical. In the past, this was accomplished by manually throwing a three-gang switch. With the advent of remote controls and timing devices, the magnetic motor starter was developed to function upon energization through a single electrical impulse from a push button station or a remote timing device.

Although multi-switch timing devices have been in common use for many years for sequence timing, they have not been used for three-phase circuits due to the fact that the normally slow rotation of the cam shaft makes it impossible to even approach a simultaneous make of three separate switches.

Now it follows that my invention is novel in that the timer caul shaft is quickly rotated at the instant of initiation of the timed cycle, by which means the three circuits to the motor are made practically simultaneously.

The initial quick rotation of the cam shaft is accomplished by cocking a spring loaded pawl which, when released, throws the cam shaft in a rotative motion ahead of the driving arm secured to the timer motor output shaft.

The system which I have devised for accomplishing the quick initial rotative motion offers an action which follows the initial motion enabling a cam shaft to rotate freely ahead of its driver so as to make three circuits simultaneously. Such constitutes the main and basic concept of this invention.

Broadly speaking, this invention comprehends the elimination of the conventional magnetic starter or the magnetic contactor, it being understood that essentially mag is necessary only'to drive the operating lever inwardly and at the inner terminal of the inward stroke to release same so as to allow it to return. By such action, the motor is energized, but, because a drive pin will have been thrown ahead of a driving arm, it will remain stationary until the motor catches up with it. There following, it will drive a series of cams through the remainder of the cycle.

It has previously been impossible, in the case of a timer, to make several circuits simultaneously since the speed of rotation of the timer has been too slow.

The desideratum, in this timing situation, is to make three switches as quickly as possible so that, when the operating lever is actuated outwardly, as by its being released to return to a normal non-operative position, the effect is to throw the switches into the on positions thereof.

Basically, such is accomplished by advancing a cam shaft ahead of the driving motor wherefor the switches remain in their on positions until the shaft of the motor rotates around and picks up the driving points and drives them around through a cycle, following which they drop off into the dwell of the cam which achieves close to a simultaneous break.

In the known prior art, it is common to use a timer with a magnetic starter disposed adjacent thereto. What has led to the present invention has been the demand for a lower cost timer, and toward that end, I have accomplished the elimination of the starter, all so as to lower costs appreciably, starters being notoriously expensive.

In a typical installation involving a three-phase system, the three-phase lines are placed across three switches, while their opposite sides are so connected as to make a circuit with the three-phase motor. When the circuit is made, it is so designed as to hold the motor in on position for a predetermined time period.

For practical purposes, as for example, in the case of commercial dishwashing machines, the machine may be started, as for example, by a l-horsepower pump motor which may serve to pump water around and within the machine for a time interval, say of one minute duration. Following same, the motor may shut off.

Two of the contact switches would be connected by legs of a three-phase circuit for energizing the timing motor. Such is a typical use of three contact points, wherein a motor is timed, which motor recirculates water within the apparatus.

Herein, I provide a timer and three cams mounted upon the drive shaft of said timer, which cams rotate so as to cut in and out the three switches of a three-phase system, with the cam shaft being thrown ahead of its driver.

In the operation of a dishwasher using my invention, the operator will push the actuating plunger in. On its way in, it will cock the mechanism and lock it in the cooked position, and on its return stroke, will release a pawl which drives the cam shaft ahead. In its movement ahead, it will simultaneously make three circuits. One phase of the system will be directed to the timing motor so that the timing motor will start at the same time that the three switches are made. The cam shaft will now have been advanced ahead of the driving arm of the timing motor. As the timer moves ahead, or the arm from the timer moves ahead, it will engage a pin in one of the cams and continue to drive the cam shaft through a revolution. At the end of that revolution, all three circuits will be broken.

The circuits connected to the three-phase motor will be broken, and the circuit connected to the timing motor will be broken, and the apparatus will then be in a position to recycle by once again depressing the plunger.

It will be understood that any motor having the desired speed of rotation may be employed to produce the desired timing cycle.

The objects of the invention are susceptible of attainment by use of constructions different in certain respects from that disclosed, such as minor changes and variations in dimensions, shape, form, proportion, integration,

cooperation of material and/or type of subassembly and accessory, all without departing from the underlying principles, salient features, scope and spirit hereof.

While all of these objects are attainable in the preferred and disclosed embodiment, it is to be understood that, by utilizing the invention only in certain ofits as pects, certain of the objects may be attained individually or in sub-groups without necessarily attaining all of the objects. That is, while the advantages of the invention as here outlined are best realized when all of its features and instrumentalities are combined, useful embodiments may be produced involving less than the whole.

The characteristic features which I consider to be novel with my invention, as to its construction and organization and as to its method of operation, will be better understood from a consideration of the following detailed description forming a part of this specification, when read in conjunction with the illustrations in the accompanying drawings, wherein like characters of reference are employed to designate like or corresponding parts throughout the several views and in which:

FIG. 1 is a top plan view of the timer of the invention;

FIG. 2 is an end elevational view of the timer of the invention with portions removed for purposes of clarity; and

FIG. 3 is a simplified wiring diagram of the timer of the invention.

In the following description and in the appended claims, various components and details thereof will be identified by specific names for purposes of convenience. Although specific terms and expressions are employed for purposes of identifying various components, they are used in a generic and descriptive sense only. The phraseology or terminology herein employed is not for the purpose of limitation and terms and expressions are intended to be as generic in their application as the art will permit. They are not intended to exclude any reasonable equivalents of the features shown and described or portions thereof.

With continued reference now to the drawings, which illustrate a typical and preferred embodiment of the invention for the purpose of disclosure and form a part of this specification, I have shown a timer which includes a pair of spaced, parallel end plates and 12 having a face plate 14 secured thereto as by rivets 16 or the like.

Elongated, transversely-extending spacers 18 will be disposed between the end plates 10 and 12 and will have screws 20 threadedly engaged therein and in said end plates, so as to further support said plates.

Elongated bolts 22 will extend between the end plates 10 and 12 and will have switches 30, 32, and 34 sleeved thereon, for purposes as will subsequently be apparent.

A timer motor 44) will be secured to end plate 10 by any suitable means and will have an output shaft 42 ex tending through said end plate and into a bar 44 disposed on the opposite face of said end plate. Bar 44 will have a set screw 46 extending therethrough to contact output shaft 42 and secure said bar relative to said shaft.

An arbor 48 will be keyed at one of it ends to bar 44 and will be journalled at its opposite end in end plate .12.

Arbor 48 will carry cams 50, 52 and 54, with said cams being maintained in spaced position on the arbor by means of spacers 56 disposed therebetween.

Each cam will be aligned with a contact arm 60 carried by one of the switches 30, 32 and 34 and will have a dwell 62 in its outer contour in which the end of its respective arm will be receivable, it being understood that the contact arm rides on the outer periphery of its respective cam, as the latter rotates.

Contact points 64 will be provided on each of the switches 30, 32 and 34 for elfectuating closing and opening of the switches upon contact or loss of contact with their respective contact arms 60.

A trigger type mechanism is employed for actuating the three-phase circuit of the apparatus and will include a plunger or lever 76 having offset arms 72 and 74 at its opposite ends. Arm 72 will be of appropriate size to be easily depressed or grasped' by the operator, and arm 74 will have an end of a tension spring 76 afiixed thereto. The opposite end of spring 76 will be fixed to face plate 14.

As best seen in FIG. 2, lever 70 will be slidably mounted upon end plate 10 by means of bolts 78 extendable through elongated slots 80 at opposite ends of the lever into said end plate. By means of this construction, lever 70 may be easily reciprocated relative to end plate 10 and bolts 78.

A lever 82 and a bell-crank or lever 84 are pivotally mounted upon end plate 10. A coil spring 96 is fixed at one end at 92 to lever 82 and at its opposite end at 94 to bell-crank 84, for purposes as will be apparent.

A actuator lever 96 is pivotally mounted at 93 to said bell-crank and also has a coil spring 1% fixed at one end at 94 to the bell-crank and at its opposite end at 102 to actuator lever 96.

A pin 1194 fixed to bell-crank 84 extends through a slot 106 provided in actuator lever 96. An elongated coil spring 108 will be fixed at one end to pin 104 and at its opposite end to end plate 10.

A pin 11!) will be fixed to plunger or lever 70 and will be so disposed as to extend into the plane of both lever 82 and bell-crank 84.

Similarly, a pin 112 will be provided on a side face of cam 50, and will extend into the plane of actuator lever 96.

Having described the manner of construction of my timer, its method of operation will now be disclosed.

To actuate the timer, plunger 70 is moved, in the direction of the arrow a in FIG. 2, causing pin 110 to contact bell-crank 84, whereupon said bell-crank rotates on its pivot 88. Continued inward movement of the plunger and rotation of the bell-crank moves pin 104 from the lower end of slot 106 in actuating lever 96 to the upper end of the slot, where it exerts sufficient force upon said actuating lever to cause it to rotate upon pivot 98 in a counterclockwise direction. As best seen in FIG. 2, actuating lever 96 is provided with an inclined surface 114 vsvherefore said lever can ride along pin 112 fixed to cam When the operator has completely depressed plunger 70, the inclined surface 114 of the actuating lever will have cleared pin 112, but an additional inclined surface 116 disposed tangential to surface 114 now rests upon pin 112.

In addition, lever 82 will have been caused to rotate upon pivot 86 by the movement of the bell-crank, wherefore a toe portion 118 of lever 82 will have now moved into interengagement with a toe portion 120 provided on the bell-crank so that the trigger mechanism is now cooked and ready to actuate the timer.

At this time, the operator releases his pressure upon plunger 70, whereupon spring 76 efi'ectuates a retrograde movement of the plunger whereby pin 110 strikes the side of lever 82 to release it from its engagement with toe portion 120 of the bell-crank, permitting the reverse rotation of the bell-crank and actuating lever 96 in a clockwise direction.

As the actuating lever rotates, inclined surface 114 thereof rides along pin 112 fixed to cam 50 causing said cam and cams 52 and 54 to move in the direction of the arrow b in FIG. 2, wherefore contact arms 60 are moved out of dwells 62 in their respective associated cams to close the switches and to actuate the timing motor.

It will be understood that the tension exerted by the respective springs 76, 90, 100 and 108 causes the trigger mechanism to travel quite rapidly in its retrograde movement. Thus, it may be properly stated that actuator lever 96 kicks cam 50 ahead into rotation.

After the timer motor is actuated, as described above,

the output shaft rotates bar 44 causing it to engage pin 112 on cam 59 to continue the rotation of arbor 48 and the cams.

As aforementioned, rather than having any actuation of the timer on the in-stroke of the plunger, where it might receive rough usage by the operator, the mechanism is started on the back-stroke following the moment when the operator will have had no choice but to release the plunger so as to lead to the starting function. Once it is released, the trigger mechanism will kick cam 50 into rotation.

The operator must press down and let the plunger come back. Should the plunger not be pressed inwardly far enough, it will be allowed to come back and nothing will happen. It must be depressed inwardly all of the way.

In the wiring diagram shown in FIG. 3, the switch means for the timing motor is tied in with the first and second legs of the three-phase circuit.

In FIG. 3, L and T designate line and terminal respectively for switch 30, L and T designate line and terminal respectively for switch 32, and L and T designate line and terminal respectively for switch 34.

From the foregoing, it is obvious that I have provided a truly novel timing device for making a circuit without the use of a magnetic starter.

It is believed that the gist of the invention will be clearly understood from the foregoing disclosure and accordingly, further analysis thereof at this point is considered unnecessary, as I have, in accordance with the provisions of the patent statutes, described the construction and principle of operation of my invention together with the apparatus which I believe to represent the best embodiment thereof, to the end that others can, by applying current knowledge, readily adapt it for various applications without omitting features which, from the standpoint of prior art, fairly constitute essential characteristics of its generic and/ or specific aspects. The substitution of equivalents and other changes, modifications. and alterations as circumstances may suggest or render expedient, are reasonably contemplated, the invention being susceptible of such without departing from its real spirit or underlying principles.

I claim:

In a timing device for cyclically controlling a number of two-position switches in the starting of a threephase motor by completing the three circuits simultaneous 1y, comprising in combination, a pair of spaced interconnected end plates, a trio of circuit making and breaking devices connected to the three-phase motor and mounted in side-by-side relation between the end plates of said pair thereof and each constituted by a switch carrying a contact pin movable between make and break positions and supporting a #cam follower movable between a con tacting position with the contact pin in the make position and a non-contacting position with the contact pin in the break position, a timer motor fixedly secured to and having an output shaft extending into the space between the end plates of said pair thereof, certain of the switches of the circuit making and breaking devices of said trio thereof being electrically connected to said timer motor, a driving arm secured to the output shaft of said timer motor, an arbor mounted between the end plates of said pair thereof, and having a common rotating axis, -a trio of identical peripherally-dwelled rotary cams fixed in spaced side-by-side relation upon said arbor and axially movable on the common rotating axis thereof, each cam of said trio thereof activating and deactivating one of the switches of said trio of circuit making and breaking devices by motivating the contact follower thereof into engagement and disengagement with the contact pin thereof, a manually actuable spring-loaded cocking plunger slidably mounted upon one of the end plates of said pair thereof and being rectilinearly movable in inwardcocking and outward-firing direction, a pawl and bell crank each pivotally mounted upon the named one of the end plates of said pair thereof and being interlockable with each other upon movement of said cocking plunger in inward-cocking direction and being releasable from each other upon movement of said cocking plunger in outward-releasing direction, a spring-loaded slot-ted actuating lever being pivotally mounted upon said bell crank and being aotuable thereby according to inward and outward movement of said cocking plunger, and a pin fixed to one of the cams of said trio thereof and being extendable into the plane of and engageable with said actuating lever for mechanically axially advancing the cams of said trio thereof and said arbor through a predetermined angular increment during the movement of said cocking plunger in inward-cocking direction for urging the cams of said trio thereof ahead of said driving arm and the making of the switches of the circuit making and breaking devices of said trio thereof and the resultant energization of said timer motor and being further extendable into the plane of and engageable withsaid driving arm for the continued rotation of said arbor and the cams of said trio thereof through a revolution for the breaking of the switches of said trio of circuit making and breaking devices preparatory to recycling.

References Cited in the file of this patent UNITED STATES PATENTS 3,015,003 Simmons Dec. 26, 1961 

